Dental trays are receptacles that are used to carry a medicine or dental hygiene materials, such as bleaching agents or fluoride application, and apply them to the teeth. It confines the material next to the teeth during the application. The thin dental tray of this invention is also suitable for use in creating provisional crowns. Because of its thinness, hardness and the accuracy of the impression it takes, it is equal to more expensive custom trays made over gypsum molds and models.
There are two types of dental trays: stock and customized. Stock trays are pro-fabricated into a variety of standard sizes. They are used only for preliminary procedures and to produce impressions for casting as an interim step to creating more accurate dental trays and models of teeth. Custom trays are made by a dentist or technician by molding a material over a gypsum model of the patient's teeth. In order to get the gypsum model, a preliminary impression is made from the patient's teeth. The model requires at least one dental visit and requires a laboratory to construct the gypsum model.
Once the model is made, the customized dental tray is formed by the dentist or lab according to the limitations of the materials to be used for the tray. If the tray is made of shellac or thermoplastic sheets, the tray may be formed in a vacuum forming machine or other machine which exerts pressure. The sheets are placed in a soft state over the model and pressure is applied while the material sets.
This method requires additional work to finish the tray by removing excess material and doing a final fit of the patient, requiring at least one more visit to the dentist. The result is a customized tray, but at a large cost of time and professional service. U.S. Pat. No. 4,401,616 is an example of this method wherein the material is a thermoplastic such as Polyform. Similarly, U.S. Pat. No. 4,569,342 discloses another thermoplastic, methyl methacrylate, that is heated and formed over a gypsum cast. Both require trimming.
Another variation of this method is described in U.S. Pat. No. 5,112,225, where polycaprolactone polymer is used to make a dental tray, again using a gypsum model. The polycaprolactone polymer is then formed over the teeth by the dentist or technician.
In each of these prior methods, the customized dental tray depends upon a model first created from an impression, after an office visit and with the aid of a professional. The final tray then is made after another visit and additional time with a professional. The time and expense of such a tray can be very great. The majority of the preliminary work, such as the initial impression, the model, and the interim products, is not usable for any other patient. If the patient's teeth structure changes, even the patient cannot make use of these products.
The invention disclosed in U.S. Pat. No. 5,076,791, uses ethylene vinyl-acetate and creates a customized dental tray without the necessity of a gypsum model. The resultant tray is thicker than the thin tray of this invention, which may cause discomfort. Additionally, it is not hard at normal temperatures, as is the thin inner tray of this invention.
This invention addresses these problems and creates a hard, thin dental tray, suitable for many types of dental and at home procedures and uses. The thin inner tray is customizable to the same accuracy as more expensive custom trays created on a model, but at a fraction of the cost in time, professional expertise or equipment. The outer tray can be used separately for fluoride gel applications. The thin dental trays can be customized and molded in the home or outside of a dental office. These dental trays can be used in third world countries or in rural areas.
It is another object of the present invention to provide a method for making a hard, flexible custom dental tray without the necessity of intermediate models, trays or special equipment or expertise.